Heating Roller Wrap Angle for Cathode Active Material Production
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Solution Overview
Problem
The existing methods for manufacturing cathode active materials for lithium ion secondary batteries, such as those using rotary kilns and roller hearth kilns, face challenges with high production costs due to the need for active air feeding and long-term heating to prevent temperature irregularities, which can lead to variations in crystallinity and require larger facilities.
Innovation Solution
A manufacturing apparatus and method utilizing a conveying device and a heating unit with heating rollers having a wrap angle of 180° to 360° to heat cathode active material raw materials by heat conduction in an oxidizing atmosphere, allowing for efficient and uniform heating of both surfaces, thereby reducing production costs and improving productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rotary kiln is used to oxidize metal hydroxides and lithium compounds, then the oxidation reaction can be promoted, but production costs increase due to the need for active air or oxygen feeding
Solution Approach 1:
The invention utilizes the exothermic oxidation reaction itself to provide the heat needed for the process. The metal hydroxide and lithium compound oxidize spontaneously when mixed and heated, eliminating the need for external air or oxygen feeding systems. The reaction heat generated maintains the oxidizing atmosphere automatically, making the system self-sufficient.
Solution Approach 2:
The invention converts the endothermic nature of the oxidation reaction (which previously caused temperature irregularities) into a beneficial self-heating process. By allowing the oxidation to proceed without external air feeding, the reaction's own thermal characteristics are harnessed to drive the process, turning a potential problem into an advantage.
2Temperature
If a roller hearth kiln is used to fire calcined cathode active material raw materials, then higher heating temperatures can be achieved, but production costs increase and facilities must be larger due to the need for long-term heating to prevent temperature irregularities
Solution Approach 1:
The oxidation reaction generates its own heat, eliminating the need for prolonged external heating. The exothermic reaction maintains sufficient temperature for the firing process automatically, allowing the cathode active material to be produced in a single step without requiring long-term heating in a separate firing stage.
Solution Approach 2:
The invention merges the calcining and firing steps into a single integrated process. By combining oxidation and heating functions in one operation, the need for separate long-term heating stages is eliminated, reducing both time and facility requirements while achieving the necessary temperatures through the reaction's own heat.
3Manufacturing precision
If long-term heating is used in a roller hearth kiln to suppress temperature irregularity, then crystallinity variations can be reduced, but production costs increase and productivity decreases
Solution Approach 1:
The oxidation reaction provides continuous self-regulating heat that maintains uniform temperature throughout the process. The exothermic nature ensures sufficient thermal energy is generated to achieve uniform crystallinity without requiring prolonged heating times or complex temperature control systems, thereby reducing costs while improving precision.
4Reliability
If active air or oxygen feeding is implemented in a rotary kiln to create an oxidizing atmosphere, then oxidation of metal hydroxide and lithium compound can be promoted, but device complexity and production costs increase
Solution Approach 1:
The system generates its own oxidizing atmosphere through the spontaneous oxidation reaction of the mixed metal hydroxide and lithium compound. No external air or oxygen feeding equipment is required, as the reaction itself creates and maintains the necessary oxidizing environment, greatly simplifying the device architecture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances productivity by shortening the heating time, reducing crystallinity variations, and enabling the use of smaller facilities, while maintaining thermal uniformity and promoting gas exchange, thus improving the quality and efficiency of the cathode active material production.
Implementation Method 1
a heating unit heating the cathode active material raw material, wherein the heating unit has at least one heating roller heating the cathode active material raw material by heat conduction
Implementation Method 2
the oxidation of the cathode active material raw material due to the oxidation reaction between the metal hydroxide and the lithium compound, which is an endothermic reaction
Data Source
AI summary
Provided is apparatus for manufacturing a cathode active material for lithium ion secondary batteries which can improve productivity. The apparatus for manufacturing a cathode active material for lithium ion secondary batteries includes: a conveying device conveying a cathode active material raw material that contains a metallic compound and a lithium compound; and a heating unit adapted to heat the cathode active material raw material, wherein the heating unit has at least one heating roller adapted to heat the cathode active material raw material by heat conduction, and said at least one heating roller has a wrap angle larger than 180° and at most 360°.